1. Field of the Invention
The present invention relates to a multi-energy system which can perform an air conditioning operation, generate electric power and also supply hot water by using a gas engine.
2. Description of the Related Art
The demand of electric power reaches its peak in the summer season. However, the overall use efficiency of the primary energy in Japan has been low in the summer season because the availability factor of power plants is low. For the purpose of cutting the peak in the summer season, a gas heat pump type air conditioner in which a compressor is driven by using a gas engine has been popularly used.
FIG. 1 shows a conventional gas heat pump type air conditioner 101. The conventional gas heat pump type air conditioner 101 is equipped with a compressor 103, a four-way valve 105, an outdoor heat exchanger 106, an outdoor expansion valve 107, indoor expansion valves 108, indoor heat exchangers 109 and an accumulator 110, which are successively connected through a refrigerant pipe 104 to the compressor 103 in this order, and also equipped with a gas engine 102 for driving the compressor 103.
In the gas heat pump type air conditioner 101, when the four-way valve 105 is switched to its cooling side, the outdoor heat exchanger 106 and each indoor heat exchanger 109 function as a condenser and an evaporator respectively to perform cooling operation. On the other hand, when the four-way valve 105 is switched to its heating side, the outdoor heat exchanger 106 and each indoor heat exchanger 109 function as an evaporator and a condenser respectively to perform heating operation.
The gas engine 102 is supplied with fuel gas fed from a fuel supply system 111, and actuated with the fuel gas. During the actuation of the gas engine 102, the waste heat of the gas engine 102 is transferred to a discharge gas heat exchanger 112 to be heat-exchanged with engine cooling water. The engine cooling water thus heat-exchanged is circulated by a cooling water pump 113, and the heat of the engine cooling water is radiated from a radiator 114.
However, the peak-cut in the summer season cannot be implemented even by using the gas heat pump type air conditioner 101 thus constructed because the installing number of electric heat pump type air conditioners in which compressors are driven by electric motors is still increased, and thus the gap in power demand between the seasons is still large.
Further, in the gas heat pump type air conditioner 101, the waste heat of the gas engine under cooling operation is normally discharged with no use, and thus the use efficiency of energy is lower under the cooling operation. A co-generation system has been proposed from the viewpoint of the use efficiency of energy. According to the co-generation system, a gas engine is actuated to drive a power generating apparatus for generating electric power, and at the same time the waste heat of the engine is withdrawn to heat water and then supply hot water thus obtained.
In the co-generation system, however, when a power-generating load is high and a hot-water supplying load is low, that is, when these loads are unbalanced with each other, the waste heat of the engine cannot be sufficiently withdrawn and thus the use efficiency of energy is low.
Further, when the power generation is continuously carried out by actuating the engine and the hot water supplying operation is properly carried out in the co-generation system, a part of required power demand is furnished over year by the co-generation system, and thus the gap in power demand between the seasons cannot be still moderated.
The present invention has been implemented in view of the foregoing situation, and has an object to provide a multi-energy system which can moderate the gap in power demand between seasons.
In order to attain the above object, according to the present invention, a multi-energy system including a gas heat pump type air conditioner in which a compressor equipped in an outdoor unit is driven by a gas engine, and a power generating apparatus having a power generator which is driven by the gas engine to output AC power, is characterized in that the power generating apparatus further includes a first converter for converting AC power output from the power generator to DC power, and a second converter for converting the DC power thus obtained in the first converter to AC power having a specified frequency and then outputting the AC power thus obtained to electric equipment.
The above multi-energy system further includes a hot water supplying apparatus for withdrawing the waste heat of the gas engine to heat water and supplying hot water thus obtained.
In the above multi-energy system, the hot water supplying apparatus includes a hot water tank for accumulating the waste heat of the gas engine in the form of hot water.
In the above multi-energy system, the hot water supplying apparatus further includes a discharge gas heat exchanger for heat-exchanging the waste heat of the discharge gas from the gas engine with engine cooling water, a cooling water pump for circulating the engine cooling water, and an intermediate heat exchanger for heat-exchanging the engine cooling water with heat medium, the heat medium being heat-exchanged with water in the hot water tank to obtain the hot water.
In the above multi-energy system, the power generating apparatus outputs the AC power in the hot water supplying operation of the hot water supplying apparatus.
In the above multi-energy system, the power generating apparatus outputs the AC power in the cooling or heating operation of the gas heat pump type air conditioner.
According to the present invention, the gas heat pump type air conditioner is actuated by the gas engine to perform the air conditioning operation, and the power generator of the power generating apparatus is drive by the same gas engine to output AC power having a specified frequency through the first and second converters, so that an air conditioner having a compressor driven by electronic equipment such as a power generator or the like can be actuated with the AC power output from the power generating apparatus. As a result, the peak-cut of the power demand, particularly in the summer season, can be implemented, and thus the gap in power demand between the seasons can be moderated.
Further, the rotational frequency of the gas engine is varied due to variation of an air conditioning load of the gas heat pump type air conditioner, and thus the output power from the power generator driven by the gas engine is also varied. However, the AC power output from the power generator is temporarily converted to the DC power by the first converter, and then the DC power is converted to the AC power having the specified frequency. Therefore, the AC power output from the power generating apparatus can be systematically linked to commercial power, that is, the AC power can be used as commercial power, and thus normal electric equipment can be actuated with the AC power output from the power generating apparatus.
Still further, during the actuation of the gas engine, the hot water supplying apparatus is driven by using the waste heat of the gas engine to make water hot, so that the use efficiency of energy can be enhanced.
Still further, through the actuation of one gas engine, the air conditioning operation is carried out by the gas heat pump type air conditioner, electric equipment is actuated by using the power generating apparatus, and water is made hot by using the hot water supplying apparatus. Therefore, the energy can be excellently efficiently used.
Still further, the hot tank for accumulating the waste heat of the gas engine in the form of hot water is disposed in the hot water supplying apparatus, and thus hot water obtained in the hot water supplying apparatus can be used at any time when it is needed.